A water tank of 1000 liters capacity is connected to a tap, which can fill at the rate of of 20 liters per minute and water is let out at the same time at the rate of 6 liters per minute.After an hour the outlet is shut off.Find how long will it take now for the tank to become full?
During the first hour the water tank fills at the rate of 20 - 6 = 14 lites per minute.
After one hour 14 * 60 = 840 liters will be in the tank.
So, 1000 - 840 = 160 liters remain for filling.
Now the rate is 20 liter per minute.
Let's find the rest of the time: 160 / 20 = 8 minutes.